Question

Lichens can be used as:

A) Bioindicator for water and air pollution

B) Bioindicator for radioactive and air pollution

C) Bioindicator for noise and air pollution

D) Bioindicator for soil and air pollution

Answer 1

Fungi and algae are related symbolically. Fungus give shelter to the algae and the algae provide food to the fungi. Lichens are rootless. They receive all the nutrients from the atmosphere. Lichens are very sensitive to atmospheric pollutants such as sulfur dioxide since they derive their water and essential nutrients mainly from the atmosphere rather than from the soil. Lichens have the ability to bind elemental pollutants and radioactive metal with their fungal mycelium where they concentrate them over time.

Compared with most physical/chemical monitors, they are inexpensive to use in evaluating air pollution as they are able to react to air pollutants all year round.

Complete answer:

Lichens are the ‘canaries in the coal mine’ of N deposition. Lichens are widely used as bioindicators. They can be used as air pollution indicators, especially sulfur dioxide in the atmosphere. They are very good at absorbing water and nutrients from the atmosphere to grow. They are composite organisms that arise from algae or cyanobacteria. Lecanora, candelariella, Dirinaria, Buelia, Laurera, Graphis, Cryptothecia etc, are some lichens that indicate the presence of pollutants in the air.

So, lichens are the bioindicator for radioactive and air pollution. So the right answer will be option B.

Note: There are some species of lichen that are more tolerant of N than others. If an increase in Nitrogen tolerant species is combined with a decrease in N sensitive species this may indicate an increase in atmospheric N deposition. Lichens are categorized into four groups. Those are, leprose, crustose, foliose and fruticose. They come in many colours. Some have special pigments such as yellow usnic acid that can give a red, orange, yellow or brown colour.